In this section we look at appendix cancer and pseudomyxoma peritonei (PMP), how they are diagnosed and treated, as well as where to go for additional information and support services.
Learn more about:
- Overview
- About the appendix
- What is appendix cancer?
- Types of appendix cancer
- What is PMP?
- How common are appendix cancer and PMP?
- What are the risk factors?
Overview
Many people feel shocked and upset when told they have cancer. You may experience strong emotions after a cancer diagnosis, especially if your cancer is rare or less common like appendix cancer or PMP.
A feeling of being alone is usual with rare cancers, and you might be worried about how much is known about your type of cancer as well as how it will be managed. You may also be concerned about the cancer coming back after treatment. Linking into local support services can help overcome feelings of isolation and will give you information that you may find useful.
About the appendix
The appendix is a small tube that usually sits on the lower right side of the abdomen. It hangs off the end of the caecum, which is a pouch at the start of the large bowel. The appendix does not have a clear function, but is thought to store gut bacteria and may play a role in the immune system to help prevent disease.
Front view of the abdomen and appendix
Side view of the abdomen
What is appendix cancer?
Appendix cancer occurs when cells in the appendix become abnormal and keep growing and form a mass or lump called a tumour.
The type of cancer is defined by the particular cells that are affected and can be benign (non- cancerous) or malignant (cancerous). Malignant tumours have the potential to spread to other parts of the body through the blood stream or lymph vessels and form another tumour at a new site. This new tumour is known as secondary cancer or metastasis.
Types of appendix cancer
The most common types include:
| Mucinous adenocarcinoma | These start in epithelial cells that line the inside of the appendix. They can produce mucin (a jelly-like substance) and spread to other parts of the body, including the peritoneum, which is a sheet of tissue that lines and protects organs in the abdomen (belly). |
| Neuroendocrine tumours (NETs) | These form in neuroendocrine cells inside the appendix. The neuroendocrine system is a network of glands and nerve cells that make hormones and release them into the bloodstream to help control normal body functions. Appendiceal NETs are often found at the tip of the appendix. For more on this, see our section on Neuroendocrine tumours (NETs) and visit NeuroEndocrine Cancer Australia. |
| Goblet cell carcinoma (GCC) | These have features of both a NET and adenocarcinoma but behave more like an adenocarcinoma, which can be more aggressive. |
| Colonic-type adenocarcinom | These may behave like colon (large bowel) cancer and are often found at the base of the appendix. |
What is PMP?
Pseudomyxoma peritonei (PMP) is a rare tumour that grows slowly and causes a build-up of mucin (a jelly-like substance) in the abdomen and pelvis, giving rise to the name “jelly belly”. Several other diseases may also be associated with “jelly belly” including mucinous adenocarcinoma, or may resemble features of PMP including mucinous tumours in the bowel.
PMP often starts in the appendix but can also start in other organs such as the large bowel and ovary. While it doesn’t spread to other parts of the body, PMP can put pressure on important organs as it continues to grow and this may cause problems.
How common are appendix cancer and PMP?
Both appendix cancer and PMP are rare. According to Australian Institute of Health and Welfare (AIHW) data, less than 900 cases of appendiceal cancer are diagnosed each year. The most common types are seen in middle-aged people, with the typical age at diagnosis about 40 to 60 years.
PMP is also rare with about 1 or 2 cases per 1,000,000 people each year. It is more likely to be diagnosed in people aged 40 years or over. Women may be diagnosed slightly more often and at an earlier stage than men, after a mass or lump is found in their ovary.
What are the risk factors?
The causes of appendix cancer and PMP are not known. There are no clear risk factors and neither appear to run in families. Increasing age, however, can increase the risk of appendix cancer.
→ READ MORE: Appendix cancer and PMP symptoms
Key resource
The information on this page is also available for download.
John Henriksen, Consumer; Prof David Morris, Surgical Oncologist, St George Hospital, Sydney, NSW; Caitriona Nienaber, 13 11 20 Consultant, Cancer Council WA.
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